Wireguard VPN full network setup

I need to configure a series of routers with OpenWRT and Wireguard as clients of a corporate Wireward network. I am attaching a small drawing where you can see the architecture we are looking for. We have different 4G routers that behind them have one or more devices with debian 11, ESP32, sensors, network cameras and some other devices. These routers, as well as the devices, have to be accessible and be connected to the servers and client computers that we have in our facilities. Based on the experience in past projects, the architecture that we have begun to deploy consists of a WG Server in a VPS in the cloud that acts as a VPN server. On the other hand, the rest of the devices (Routers) work as clients, allowing from any point of the network to access or transmit data to other devices that are within the VPN network, either directly or through another router with a VPN client. The routers we are using are GL-Inet with OpenWRT as the operating system and we are currently able to connect them to the client and get them into the network. We managed to pin between machines and routers but not access the devices behind each of them. On the other hand, although, second stage of this project, we would need to configure the WG Servers in a high availability scheme so that in the event of a crash it will jump to another machine and the service will be cut as little as possible. One thing about the configuration, I don't want to do it over port redirections on the routers, I want to be done just with VPN configuration, being able to see the devices from different networks. Being clear, the test to check if the job was done correctly is that I will have a PC with a VPN profile and if I ping any device of the network map I need to receive ping back and be able to connect to it, any device behind a router with the vpn profile as a camera or other. Ask for any question. Job must be done in one day first stage and three more days for the other two stages.